Экологическая медицина = Ecological medicine. Учебное пособие

When comparing the UV index values ​​with MED, it was found that 10 units of the UV power index correspond to erythema dose of 4.3 MED/h. Hence, the UV-unit index is 0.43 MED/h.

Table 2.2. Types of skin sensitivity

Since each value of the UV index is characterised by its own high density of the UV radiation flow, in order to choose a safe exposure time, it is necessary to calculate the duration of the sunbathing time, depending on the type of skin sensitivity.

Following the recommendations of international organisations, for non-pigmented skin of all sensitivity types the permissible level is a dose of 0.4 MED per day; for an individual with tanned skin of sensitivity type II the UV radiation permissible level is a dose of 1 MED per day.

Calculation procedure:

1.  Calculate the value of the erythema dose rate (DR) at a given value of the UV index: DR (MED/h) = UV index × 0.43 MED/h.

2.  Calculate the time in hours for which, with a given value of the UV index and the type of skin sensitivity, an acceptable daily dose will be formed: t (h) = PL/DR.

3.  Transfer the resulting time into minutes: t (min.) = t (h) × 60. Note that the maximum permissible cumulative (for one year) MED

value per year for skin type II is recommended to be 50. For the types III and IV – 70 and 90 MED, respectively.

Skin sensitivity test. The following 10 questions should be answered to determine your skin sensitivity to UV radiation. Use ready-made answers. The answers are evaluated as follows: the first answer – 1 point, the second answer – 2 points, the third answer – 3 points, the fourth answer – 4 points. Add up all the points and divide the sum by 10. Then, round the resulting number according to the existing rules. This will be your skin sensitivity type. For example, if the resulting number is 2.5, you have a borderline skin sensitivity type (between the second and third types).

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1.  Your untanned skin colour:

a)pale-pink, white-pink;

b)white;

c)slightly swarthy;

d)swarthy.

2.  Your genetically determined hair color:

a)red;

b)natural blonde / blonde;

c)from light brown to brown;

d)from dark brown to black.

3.  Your eye colour:

a)  light blue, light grey or light green; a)  blue, grey, green;

a)  hazel or dark grey; a)  dark brown.

4.  Do you have freckles?

a)  a lot; a)  a few; a)  very few;

a)  no freckles.

5.  Reaction of your facial skin to solar irradiation:

a)  very sensitive, sunburns often occur; a)  sensitive, sunburns may occur;

a)  no particular sensitivity, sunburns occur very rarely; a)  insensitive, sunburns never occur.

6.  How long can you stay in the summer sun (latitude of Belarus) at noon under a cloudless sky without getting sunburn?

a)less than 15 min.;

b)from 15 to 25 min.;

c)from 25 to 40 min.;

d)over 40 min.

7.  What skin reactions do you experience from a prolonged exposure to the sun?

a)sunburns always occur;

b)sunburns often occur;

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c)sunburns can sometimes occur;

d)sunburns are rare or non-existent.

8.  What are your symptoms of sunburn?

a)there is severe hyperemia accompanied by pain, blisters may occur; then the skin begins to peel off;

b)there is hyperemia followed by skin peeling;

c)there is slight hyperemia; skin peeling might occur;

d)there is neither hyperemia nor peeling.

9.  Does suntan occur after your single, but prolonged stay in the sun?

a)no, it’s not possible;

b)very rarely;

c)often;

d)as a rule.

10.  How does your tan develop after repeated sunbathing?

a)there may be a barely noticeable tan or no tan at all;

b)tan is formed with difficulty;

c)tan increases progressively;

d)a good tan comes on quickly.

As noted above, the action mechanism of UV radiation refers to stochastic, i.e., probabilistic. The most severe pathology arising from the action of this physical factor is malignant skin tumours. It is very important to determine the risk of this pathology based on your own individual data (skin sensitivity type, history of UV insolation, genetic data). Use the following test for this purpose.

Skin cancer risk assessment. This simplified version of the test was developed and proposed by the American Academy of Dermatology. Each feature corresponds to a certain number of points, which are given after the appropriate number of the corresponding feature. After answering all seven questions, sum up the resulting points.

1.  Your skin sensitivity type to UV radiation:

a)the type I (highly sensitive) – 4;

b)the type II (sensitive) – 4;

c)the type III (normal) – 3;

d)the type IV (insensitive) – 1.

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2.  Your eye colour:

a)  blue / green – 4; a)  grey – 3;

a)  brown – 2.

3.  What happens if you sunbathe for the first time in the summer for an hour?

a)  skin turns red, then starts peeling off – 4; a)  skin turns red followed by tan formation – 3; a)  skin immediately begins to darken – 1.

4.  The number of birthmarks on the body:

a)  a lot – 5;

a)  a few (less than 30) – 3; a)  only single spots – 1.

5.  Where do you spend most of the daylight hours in view of your professional activity?

a)  outdoors – 4;

b)partly outdoors and partly indoors – 3;

c)indoors – 2.

6.  Has any of your relatives registered skin cancer?

a)yes – 5;

b)no – 1.

7.  Your main place of residence under the age of 18:

a)areas with high solar insolation (South of Ukraine, Caucasus, Moldova, Central Asia) – 4;

b)middle belt of the European part – 3;

c)north of the European part – 2.

Table 2.3 translates the scores obtained into a skin cancer risk score:

Note: A more detailed test for skin cancer risk from UV exposure can be found online at http://www.uvinfo.narod.ru.

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Calculation of minimum sun exposure time required to provide the daily human need for vitamin D3. According to the WHO, a daily synthesis of 400 IЕ of vitamin D3 requires a dose of 60 MED per year. The daily requirement of a person for vitamin D3 is 100 IЕ for an adult, 200 IЕ for a child (4–6 years old). IE is an international unit, corresponding to 0.025 mcg of cholecalciferol or ergocalciferol.

Calculate the minimum sun exposure time per day necessary to provide the daily vitamin D3 requirement for an adult with skin sensitivity type II. Take the average annual value of the UV index in Belarus as 3.

1.  Calculate the annual dose of UV radiation required to synthesise 100 IЕ of vitamin D3:

60  MED → 400 IE,

X MED → 100 IE,

Х = 60 × 100 / 400 = 15

Consequently, according to Belarusian standards, a dose of 15 MED per year is required for an adult.

2.  Calculate the dose of UF radiation necessary for the daily synthesis of 100 IЕ of vitamin D3 in the adult body:

15  MED / 365 days a year = MED 0.04 per day.

3.  Calculate the amount of energy required for the daily synthesis of 100 IE of vitamin D3 in the adult body:

–one MED for the second type of skin sensitivity is 250 J/m2;

–250 J/m2 × 0.04 = 10 J/m2.

Consequently, the daily vitamin D3 replenishment for the second type of skin sensitivity requires an energy of 10 J/m2.

4.  If the average annual index of UV radiation in Belarus is taken as 3, then the flow density of UV radiation in this case will be:

3 / 40 = 0.075 W/m2.

5.  It is known that a watt is equal to the wave energy flux, at which 1 J of wave energy passes through an arbitrary surface in 1 second (1 W = 1 J/sec.). Therefore, the daily dose of vitamin D3 under these conditions will be formed for 133 seconds:

10 J/m2 / 0.075 W/m2 = 133 sec.

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6.  Convert time to minutes:

133  / 60 = 2.2 min.

Thus, for the synthesis of 100 IE of vitamin D3 in an adult with skin sensitivity type II, with the average annual index of UV radiation equal to 3, the minimum time of solar exposure per day is 133 sec. (or 2.2 min.) at the flux density or the UV radiation energy 0.075 W/m2 and 10 J/m2 respectively.

PRACTICE

Task 1. Identify your skin sensitivity type.

Task 2. Calculate your safe tanning time (for non-pigmented and tanned skin) if the UV index is 5.

Task 3. Assess your risk of developing skin cancer from exposure to UV radiation and suggest measures to reduce this risk.

Task 4. Calculate safe sun exposure time considering the skin sensitivity; take the annual average UV index value in Belarus as 4.

Task 5. Calculate the minimum daily sun exposure time necessary to provide the daily vitamin D3 requirement for a 5-year-old child with skin sensitivity type II.

LABORATORY SESSION

Identifying meteosensitivity at the prenosological diagnostics stage (the technique was developed at the Department of General Hygiene, Ecology and Radiation Medicine of EI “Gomel State Medical University”).

Step 1. You are to rate your well-being, mood and activity under different weather conditions. When answering a question, put “+” in the corresponding box:

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Hot

Windy

Windless

Wet

Dry

Low barometric pressure

High barometric pressure

Rain

Snow

Combination of wind and rain

Combination of snow, rain, and wind

Overcast / cloudy

Sunny

Foggy, misty

Low clouds

Thick clouds

Rapid changes during the day

No magnetic storm

Weak magnetic storms

Strong magnetic storms

2.  Your mood under different weather conditions:

Cold

Warm

Hot

Windy

Windless

Wet

Dry

Low barometric pressure

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High barometric pressure

Rain

Snow

Combination of wind and rain

Combination of snow, rain, and wind

Overcast / cloudy

Sunny

Foggy, misty

Low clouds

Thick clouds

Rapid changes during the day

No magnetic storm

Weak magnetic storms

Strong magnetic storms

3.  Your activity under different weather conditions:

Cold

Warm

Hot

Windy

Windless

Wet

Dry

Low barometric pressure

High barometric pressure

Rain

Snow

Combination of wind and rain

Combination of snow, rain, and wind

Overcast / cloudy

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Sunny

Foggy, misty

Low clouds

Thick clouds

Rapid changes during the day

No magnetic storm

Weak magnetic storms

Strong magnetic storms

The integral index is calculated by the sum of the points. For each answer: “Without change” – 0 points, “Change for the better” – 1 point, “Change for the worse” – 2 points.

Meteosensitivity is not expressed with a total up to 23 points; meteosensitivity is expressed with a score of 24 or more.

Step 2. For those who have been diagnosed with meteosensitivity, the degree of its severity is determined. For this purpose, it is necessary to answer the following questions.

Common symptoms:

1.  Is there any violation of attention or concentration? 2.  Do you have headaches?

3.  Do you feel a general weakness, loss of strength and energy? 4.  Do you experience reduced working capacity?

5.  Is there persistent fatigue?

6.  Do you have dizziness attacks?

7.  Do you have poor, superficial sleep? 8.  Is there decreased potency?

9.  Do you experience any state of inner devastation? 10.  Is there an unstable body temperature?

11.  Do you suffer from allergies?

Nervous system symptoms:

12.  Do you notice any functional disorders of the nervous system (anxiety, increased agitation, etc.)?

13.  Are there any neurasthenic manifestations (irritability, aggressiveness, etc.)?

14.  Is there a tendency to sweating?

15.  Do you experience a slight tremor in your fingers?

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